To investigate the rock weathering processes in subtropical basin in east China,we analyzed major ion compositions of rivers and precipitation samples in the Qingyi River Basin in the lower reach of the Yangtze River. In this study,the characteristics of weathering processes in the Qingyi River Basin were identified,and the rock weathering rates and consumption rates of atmospheric CO2 were estimated based on water chemistry and the forward model. The results show that the anthropogenic influences on rock weathering were not significant,which means the rock weathering in the study area was mainly induced by carbonic acid while the influence of sulfuric acid and nitric acid could be neglected. The cations of rivers were mainly contributed by weathering of carbonates (59.2％),followed by weathering of silicates (17.9％). Atmospheric precipitation and evaporites contributed 9.6％ and 5.6％,respectively. Spatially,the carbonate weathering rates and silicate weathering rates decreased in the order of tributary Huishui River in the upstream mountainous areas (32.04 t·km-2·a-1 and 20.97 t·km-2·a-1)>main stream of Qingyi River (24.12 t·km-2·a-1 and 8.91 t·km-2·a-1)>tributary Zhanghe River in the downstream areas (13.68 t·km-2·a-1 and 2.85 t·km-2·a-1). Similarly,the CO2 consumption rates from carbonates weathering and silicate weathering were in the order of tributary Huishui River (5.86×105 mol·km-2·a-1 and 3.29×105 mol·km-2·a-1)>main stream of Qingyi River (2.45× 105 mol·km-2·a-1 and 2.43×105 mol·km-2·a-1)>tributary Zhanghe River (0.77×105 mol·km-2·a-1 and 1.39×105 mol·km-2·a-1). In conclusion,carbonate weathering induced by carbonic acid was dominant in the Qingyi River Basin,with chemical weathering rates slightly lower than those of similar silicate-dominated subtropical areas in east China. The rock weathering rates in the study area differed spatially. In particular,silicate weathering in upstream mountainous areas accounted for more carbon sink of the whole Qingyi River Basin,which is of great importance for the regional carbon cycle.
subtropicalQingyi River Basinrock weatheringatmospheric CO2 consumptioncarbon sinkhydrogeology
维普
万方数据
